Space Station's Dextre Robot Passes Crucial Test

Stephen Clark | December 28, 2010 07:13am ET

This illustration depicts the Canadian Space Agency's Dextre maintenance robot at the end of the International Space Station's Canadarm2. Dextre and a Japanese module will be delivered to the ISS during NASA's March 2008 STS-123 mission.Credit: NASA

Canadian engineers
put the International Space Station's Dextre robot through a workout
last week, showing that the handyman is ready for duty when a
Japanese cargo freighter arrives at the orbiting lab in January.

Dextre relocated a
cargo transport container from one stowage location to another on the
space station's truss backbone. The maneuver was accomplished Dec. 22
and Dec. 23.

Mounted on the end
of the station's robot arm, Dextre
grappled the 974-pound cargo carrier and mounted it on a
caddy workbench on Dec. 22. Then the robot arm moved to the
container's new location Dec. 23, and with the help of engineers on
the ground, Dextre placed its cargo on a storage rack with a precise
alignment within one degree of perfection.

A set of power
controllers is packed inside the cargo transport container.

Outfitted with two
11-foot-long (3.3-meter-long) arms, Dextre is designed to assume
routine maintenance tasks outside the space station that would
normally require a spacewalk by astronauts.

Dextre's arms
include tool-grasping grippers and arm joints to give the robot
human-like skills for repair work outside the space station. [Diagram
of Dextre robot]

"When
astronauts train to do this type of task during a spacewalk, they get
to practice again and again until they are comfortable with the
procedure," said Tim Braithwaite, the Canadian Space Agency's
representative at NASA's Johnson Space Center in Houston.

Last week's
operation is billed as a final exam by Canada, which provides the
bulk of the
space station's robotics equipment. It also frees space
for the Alpha
Magnetic Spectrometer, a major international physics
experiment due to arrive at the station in April.

Dextre is commanded
from mission control in Houston, while engineers in St. Hubert, a
suburb of Montreal, stand ready to assist.

"We're
operating a new robot via remote control, doing a task that has never
been done robotically, with precision levels that have to be
near-perfect," Braithwaite said. "So this test is also
about gaining experience for the ground team and learning how to
operate Dextre's complicated systems."

Dextre will transfer
two unpressurized payloads from Japan's HTV resupply freighter to the
space station early next year.

After the HTV berths
with the station, the outpost's robot arm will pull an exposed pallet
from the spacecraft and place it on a temporary platform. Dextre will
pluck a cargo container and a spare flex hose rotary coupler from the
pallet and move the payloads to permanent positions on the space
station.

The HTV is scheduled
to launch Jan. 20 and arrive at the station one week later.

The cargo
transfer duties are the first significant operational
tasks for Dextre, which launched on a space shuttle flight in 2008.